Inert matrix fuel of SiC directional composite ZrN ceramic and preparation method and application thereof

Abstract

The application belongs to the field of ceramic fuel, and discloses a SiC directional composite ZrN ceramic inert matrix fuel, a preparation method and application thereof. The SiC directional composite ZrN ceramic inert matrix fuel is prepared by the following steps: mechanically mixing nano SiC powder and micron ZrN powder to obtain SiC directional coated ZrN powder, pre-pressing the SiC coated ZrN powder, heating to 1800-2100 DEG C in a protective atmosphere, and performing hot-press sintering or discharge plasma sintering under a pressure of 40-100 MPa. The inert matrix fuel has good oxidation resistance, corrosion resistance and high-temperature resistance, and can be applied in a nuclear reactor.

Description

Technical Field

[0001] This invention belongs to the field of ceramic inert matrix fuel technology, and more specifically, relates to an inert matrix fuel of SiC oriented composite ZrN ceramic, its preparation method and application. Background Technology

[0002] ZrN ceramics are being considered for use as an inert matrix fuel in advanced nuclear power plants due to their advantages such as high melting point, high thermal conductivity, low neutron absorption cross section, good high-temperature stability and radiation resistance, and crystal structure similar to most actinide nitrides. However, ZrN has poor resistance to oxidation and hydrothermal corrosion. Under accident conditions, if the cladding fails, the fuel's inability to withstand hydrothermal corrosion could easily lead to a major nuclear leak. Therefore, improving the oxidation and hydrothermal corrosion resistance of ZrN can buy more time for rescue after an accident. While adding second-phase materials such as AlN and CrN is commonly used to improve oxidation and hydrothermal corrosion resistance, this has not significantly improved these properties, and the content of the second phase is often high. SiC exhibits better oxidation and hydrothermal corrosion resistance. Therefore, there is an urgent need to develop an inert matrix fuel based on SiC-directed composite ZrN ceramics and its preparation method, which allows for the addition of less second phase to improve the oxidation and hydrothermal corrosion resistance of ZrN. Summary of the Invention

[0003] In order to overcome the shortcomings and disadvantages of the existing technology, the present invention aims to provide an inert matrix fuel of SiC oriented composite ZrN ceramic, which has oxidation resistance and hydrothermal corrosion resistance.

[0004] Another objective of this invention is to provide a method for preparing an inert matrix fuel of SiC-oriented composite ZrN ceramics, which can add less second phase and improve the oxidation resistance and hydrothermal corrosion resistance of ZrN ceramic inert matrix fuels.

[0005] Another object of the present invention is to provide the application of the above-mentioned SiC-oriented composite ZrN ceramic as an inert matrix fuel.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] An inert matrix fuel of SiC-oriented composite ZrN ceramic is disclosed. The SiC-oriented composite ZrN ceramic inert matrix fuel is prepared by mechanically mixing nano-SiC powder and micron-sized ZrN powder to obtain SiC-oriented coated ZrN powder; pre-pressing the SiC-coated ZrN powder into shape; heating to 1800-2100℃ and pressurizing to 40-100MPa under a protective atmosphere; and then hot-pressing sintering or spark plasma sintering.

[0008] Preferably, the mass percentage of the nano-SiC powder and the micron-sized ZrN powder is (5-15) wt%: (85-95) wt%.

[0009] Preferably, the particle size of the nano-SiC powder is 30-100 nm, the purity of the nano-SiC powder is above 99%, the particle size of the micron-sized ZrN powder is 1-10 μm, and the purity of the micron-sized ZrN powder is above 96%.

[0010] Preferably, the heating rate of the hot pressing sintering is 5-15℃ / min, the heating rate of the spark plasma sintering is 50-100℃ / min, the protective atmosphere is argon or nitrogen, and the sintering time is 10-120min.

[0011] Preferably, the inert matrix fuel of the SiC-oriented composite ZrN ceramic has a SiC phase orientedly coated around the grain boundaries of ZrN grains, which can resist oxidation for 2-4 hours at 800-1200℃ and resist corrosion for 1-3 hours at 250-360℃ and 4-18.6MPa.

[0012] The method for preparing the inert matrix fuel of SiC-oriented composite ZrN ceramic includes the following specific steps:

[0013] S1. Mechanically mix nano-SiC powder with micron-sized ZrN powder to obtain SiC-oriented ZrN powder;

[0014] S2. SiC-coated ZrN powder is pre-pressed and heated to 1800-2100℃ under a protective atmosphere and pressurized to 40-100MPa. The resulting SiC-oriented composite ZrN ceramic inert matrix fuel is obtained by hot pressing sintering or spark plasma sintering.

[0015] Preferably, the mechanical mixing speed in step S1 is 1000-3000 r / min, and the mechanical mixing time is 5-30 min.

[0016] Preferably, the pre-compression molding described in step S2 is performed by applying a uniaxial pressure of 10-20 MPa using a dry press.

[0017] The application of the SiC-directed composite ZrN ceramic inert matrix fuel in nuclear reactors.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention uses a friction mill to mechanically mix nano-SiC and micron-sized ZrN powders. Under the action of mutual collision between the powders, the small-diameter SiC particles coat the surface of the large-diameter ZrN powder, resulting in nano-SiC oriented coating of micron-sized ZrN. In the ZrN ceramic sintered with the coated powder, SiC is oriented and distributed between ZrN grains, effectively improving the oxidation and corrosion resistance of inert matrix fuels.

[0020] 2. The ceramic inert matrix fuel prepared by this invention has high SiC thermal conductivity, small neutron absorption cross-sectional coefficient, good radiation resistance and corrosion resistance, and the content of the added second phase is reduced.

[0021] 3. The inert matrix fuel of the SiC oriented composite ZrN ceramic prepared by this invention has good high temperature resistance, corrosion resistance and radiation resistance. Attached Figure Description

[0022] Figure 1 This is a microscopic schematic diagram of the inert matrix fuel of the SiC-oriented composite ZrN ceramic of the present invention. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments, but these should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0024] Figure 1 This is a microscopic schematic diagram of the inert matrix fuel of the SiC-oriented composite ZrN ceramic of the present invention. From... Figure 1 It is known that after mechanical mixing in a friction mill, silicon carbide powder is coated onto the surface of the zirconium nitride powder, and after sintering, the silicon carbide is oriented and distributed around the zirconium nitride grain boundaries. In contrast, in ordinary ball milling, silicon carbide and zirconium nitride are randomly and uniformly distributed. This indicates that mechanical mixing can achieve oriented coating of SiC phase around the grain boundaries of ZrN grains, thus producing SiC-oriented composite ZrN ceramics.

[0025] Example 1

[0026] 1. SiC powder and ZrN powder were dried in a constant temperature oven at 80℃ for 24 hours. SiC (purity 99%, particle size 100nm) and ZrN (purity 99%, particle size 10μm) were weighed at a mass percentage of 15wt%:85wt%. They were mechanically mixed in a friction mill (the distance between the elliptical rotor and the side of the chamber was 2-3cm, and the distance between the elliptical rotor and the bottom of the chamber was 0.5-1cm) at a speed of 1000r / min for 10min to obtain SiC-coated ZrN powder.

[0027] 2. SiC-oriented ZrN-coated powder is poured into a graphite mold and pre-pressed using a dry press with a uniaxial pressure of 10-20 MPa. The mold is then placed in a spark plasma sintering furnace under an argon atmosphere and a pressure of 80 MPa is applied. The temperature is increased to 2000℃ at a rate of 100℃ / min and held for 10 min. The cooling rate is the same as the heating rate, thus obtaining an inert matrix fuel of SiC-oriented composite ZrN ceramic.

[0028] The inert matrix fuel of SiC oriented composite ZrN ceramic prepared in this embodiment can resist oxidation for 2 hours at 1200℃ and resist corrosion for 1 hour at 360℃ and 18.6MPa. The swelling rate of this inert matrix fuel after neutron irradiation at 13.8dpa / 4h is <1.6%, which shows good high temperature resistance, oxidation resistance, corrosion resistance and irradiation resistance, and can be applied in nuclear reactors.

[0029] Example 2

[0030] 1. Weigh SiC (99% purity, 100nm particle size) and ZrN (99% purity, 10μm particle size) at a mass percentage of 10wt%:90wt%, and mechanically mix them in a friction mill at 1500r / min for 10min to obtain SiC-oriented ZrN powder.

[0031] 2. The SiC-oriented ZrN powder was poured into a graphite mold for pre-pressing and then placed in a spark plasma sintering furnace under an argon atmosphere. The furnace was subjected to a pressure of 80 MPa and heated to 1950 °C at a rate of 100 °C / min, and held for 20 min. The cooling rate was the same as the heating rate, thus obtaining an inert matrix fuel of SiC-oriented composite ZrN ceramic.

[0032] The inert matrix fuel of SiC oriented composite ZrN ceramic prepared in this embodiment can resist oxidation for 4 hours at 900℃ and corrosion for 2 hours at 300℃ and 8.6MPa. The swelling rate of this inert matrix fuel after neutron irradiation at 13.8dpa / 4h is <0.6%, which shows good high temperature resistance, oxidation resistance, corrosion resistance and radiation resistance, and can be applied in nuclear reactors.

[0033] Example 3

[0034] 1. Weigh SiC (99% purity, 100nm particle size) and ZrN (99% purity, 10μm particle size) at a mass percentage of 10wt%:90wt%, and mechanically mix them in a friction mill at 1000r / min for 15min to obtain SiC-oriented ZrN powder.

[0035] 2. The SiC-oriented ZrN powder was poured into a graphite mold for pre-pressing and then placed in a hot-press sintering furnace under an argon atmosphere. A pressure of 60 MPa was applied, and the temperature was raised to 1900℃ at a rate of 10℃ / min and held for 1 hour. The cooling rate was the same as the heating rate, thus obtaining an inert matrix fuel of SiC-oriented composite ZrN ceramic.

[0036] The inert matrix fuel of SiC oriented composite ZrN ceramic prepared in this embodiment can resist oxidation for 2 hours at 900℃ and corrosion for 1 hour at 300℃ and 8.6MPa. The swelling rate of this inert matrix fuel after neutron irradiation at 13.8dpa / 4h is <1.0%, which shows good high temperature resistance, oxidation resistance, corrosion resistance and radiation resistance, and can be applied in nuclear reactors.

[0037] Example 4

[0038] 1. Weigh SiC (99% purity, 100nm particle size) and ZrN (99% purity, 10μm particle size) at a mass percentage of 5wt%:95wt%, and mechanically mix them in a friction mill at a speed of 1500r / min for 15min to obtain SiC oriented ZrN powder.

[0039] 2. The SiC-oriented ZrN powder was poured into a graphite mold for pre-pressing and then placed in a hot-press sintering furnace under an argon atmosphere. A pressure of 60 MPa was applied, and the temperature was raised to 2000℃ at a rate of 15℃ / min and held for 2 hours. The cooling rate was the same as the heating rate, thus obtaining an inert matrix fuel of SiC-oriented composite ZrN ceramic.

[0040] The inert matrix fuel of SiC oriented composite ZrN ceramic prepared in this embodiment can resist oxidation for 2 hours at 1100℃ and corrosion for 3 hours at 300℃ and 8.6MPa. The swelling rate of this inert matrix fuel after neutron irradiation at 13.8dpa / 4h is <0.5%, which shows good high temperature resistance, oxidation resistance, corrosion resistance and radiation resistance, and can be applied in nuclear reactors.

[0041] Example 5

[0042] 1. Weigh SiC (99% purity, 100nm particle size) and ZrN (99% purity, 10μm particle size) at a mass percentage of 5wt%:95wt%, and mechanically mix them in a friction mill at 1000r / min for 20min to obtain SiC-oriented ZrN powder.

[0043] 2. The SiC-oriented ZrN powder was poured into a graphite mold for pre-pressing and then placed in a spark plasma sintering furnace under an argon atmosphere. A pressure of 60 MPa was applied, and the temperature was raised to 1900℃ at a rate of 100℃ / min and held for 10 min. The cooling rate was the same as the heating rate, thus obtaining an inert matrix fuel of SiC-oriented composite ZrN ceramic.

[0044] The inert matrix fuel of SiC oriented composite ZrN ceramic prepared in this embodiment can resist oxidation for 3 hours at 800℃ and resist corrosion for 1 hour at 250℃ and 4MPa. The swelling rate of this inert matrix fuel after neutron irradiation at 13.8dpa / 4h is <0.8%, which shows good high temperature resistance, oxidation resistance, corrosion resistance and irradiation resistance, and can be applied in nuclear reactors.

[0045] The inert matrix fuel of the SiC-oriented composite ZrN ceramic of the present invention has a SiC phase orientedly coated around the grain boundaries of ZrN grains. It can resist oxidation for 2-4 hours at 800-1200℃ and resist corrosion for 1-3 hours at 250-360℃ and 4-18.6MPa. It has good high temperature resistance, oxidation resistance, corrosion resistance and radiation resistance, and can be applied in nuclear reactors.

[0046] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An inert matrix fuel based on SiC-oriented composite ZrN ceramics, characterized in that, The SiC-oriented composite ZrN ceramic inert matrix fuel is obtained by mechanically mixing nano-SiC powder with micron-sized ZrN powder at a mass percentage of (5~15)wt%:(85~95)wt% to obtain SiC-oriented coated ZrN powder. SiC-coated ZrN powder is pre-pressed and then heated to 1800-2100℃ and pressurized to 40-100 MPa under a protective atmosphere, followed by hot-pressing sintering or spark plasma sintering. The nano-SiC powder has a particle size of 30-100 nm and a purity of over 99%. The micron-sized ZrN powder has a particle size of 1-10 µm and a purity of over 96%. The inert matrix fuel of the SiC-oriented composite ZrN ceramic has a SiC phase orientedly coated around the grain boundaries of ZrN grains. It can resist oxidation for 2-4 h at 800-1200℃ and resist corrosion for 1-3 h at 250-360℃ and 4-18.6 MPa.

2. The inert matrix fuel of SiC-oriented composite ZrN ceramic according to claim 1, characterized in that, The heating rate of the hot pressing sintering is 5~15 ℃ / min, the heating rate of the spark plasma sintering is 50~100 ℃ / min, the protective atmosphere is argon or nitrogen, and the sintering time is 10~120 min.

3. The method for preparing the inert matrix fuel of SiC-oriented composite ZrN ceramic according to claim 1 or 2, characterized in that, The specific steps include the following: S1. Mechanically mix nano-SiC powder with micron-sized ZrN powder to obtain SiC-oriented ZrN powder; S2. SiC-coated ZrN powder is pre-pressed and heated to 1800~2100 ℃ under a protective atmosphere and pressurized to 40~100MPa. After hot pressing sintering or spark plasma sintering, SiC-oriented composite ZrN ceramic inert matrix fuel is obtained.

4. The method for preparing the inert matrix fuel of SiC-oriented composite ZrN ceramic according to claim 3, characterized in that, The mechanical mixing speed in step S1 is 1000~3000 r / min, and the mechanical mixing time is 5~30 min.

5. The method for preparing the inert matrix fuel of SiC-oriented composite ZrN ceramic according to claim 3, characterized in that, The pre-compression molding described in step S2 involves applying 10~20 MPa uniaxial pressure using a dry press.

6. The application of the inert matrix fuel of SiC oriented composite ZrN ceramic as described in claim 1 or 2 in nuclear reactors.

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